Veterinary Services

Toxic conditions

Five mule gimmers were submitted to the Dumfries Centre from a local flock that since lambing had lost 30 out of a group of 200. Although the carcases were badly autolysed, there was evidence of jaundice and of a haemolytic crisis consistent with a diagnosis of chronic copper poisoning. This was confirmed through analysis of liver copper content, which ranged from 14,500 – 42,800 umol/kg DM (normal 314 – 7,850) and kidney copper from 3,620 – 13,900 umol/kg DM (normal <787). Following the diagnosis a farm visit was conducted during which several sheep were found with clinical signs consistent with photosensitization (figure 1; use PDF link on right). When one of these affected sheep was blood-sampled, serum aspartate aminotransferase (AST) activity was found to be 3439 iu/l (normal 20 – 60) and gamma glutamyl transferase (GGT) 527 iu/l (normal 27 – 31), consistent with significant hepatic damage, which is likely to have predisposed to the skin lesions. This group had received a proprietary ewe nut since January and no more deaths occurred after access to this was removed. Analysis of the current batch of this feed showed that it contained 16.8 mg/kg DM copper. However, examination of earlier batches of the ewe's feed, which had been retained by the manufacturer, revealed copper levels of up to 45 mg/kg.

A shearling Suffolk ram was submitted to the Inverness Centre from a flock in which there had been 25 deaths in a group of 115 being prepared for sale. A diagnosis of copper poisoning had earlier been made in this group, caused by the feeding of a concentrate that had been over-supplemented with copper. On this occasion the ram had been seen to be lagging behind when the group was moved and had died shortly afterwards. The carcase was markedly jaundiced, the kidneys were dark in colour and the orange coloured liver was found to contain 22,200 umol/kg DM of copper. Further deaths occurred in the group later in May, bringing the total number to 34. A decision was then taken to slaughter the remainder of the group, because of the risks of further cases occurring, particularly after sale and transport. This was done on the basis that chronic copper poisoning in sheep is very difficult to treat. Following slaughter the carcases did not enter the food chain.

Parasitic diseases

A total of thirty outbreaks of nematodiriasis were identified this month. In a typical case confirmed at necropsy, a two-month-old lamb at the Ayr Centre was found to have more than 20,000 Nematodirus battus present in the small intestine. Other cases at Ayr showed concurrent pulpy kidney disease and/or coccidiosis.

When two lambs died from a group of 120 Texel cross lambs on a Berwickshire unit, examination of one of the carcases revealed more than 40,000 Nematodirus battus worms.

Ayr reported the examination of faeces collected from 10 scouring lambs, aged six and eight weeks and taken some 10 days after dosing with a benzimidazole anthelmintic. All samples were found to contain Nematodirus battus eggs, ranging from 100 to 750 eggs per gram, suggesting a lack of efficacy of the anthelmintic or dosing procedures. Further monitoring of this problem is continuing.

A four-year-old Scottish Blackface ewe from Dumfries and Galloway was the second animal to die in a group of 70. There was a history of soft dung, exercise intolerance and a frothy nasal discharge. At necropsy the carcass appeared pale and there was focal areas of consolidation present within the lung tissues. In addition there was evidence of chronic fascioliasis and 5,800 Haemonchus contortus worms were detected within the abomasum.

Generalised and systemic conditions

Necrobacillosis was confirmed in a one-week-old lamb on a unit in northern Aberdeenshire. There was a history of an increase in mortality amongst young lambs, some of which showed evidence of navel ill. A lamb submitted for examination showed signs of severe septicaemia and Fusobacterium necrophorum was isolated in pure growth from the lung and liver.

The Ayr Centre investigated the loss of three lambs that were found dead during one day, in a group running with 80 ewes on a local holding. When a one-month-old lamb was examined, septicaemia due to Streptococcus dysgalactiae was confirmed at necropsy.

Alimentary tract disorders

The pigmented form of Johne’s disease was confirmed at necropsy in an emaciated, recumbent four-year-old Saanan goat. Discussions with the owner indicated that around 5% of the herd of 100 milking goats were lost annually due to emaciation.

Respiratory tract conditions

Pasteurella trehalosi was isolated in a profuse pure growth from the lungs of a Bluefaced Leicester lamb that had a severe bilateral purulent pleurisy and lung consolidation, abscessation and necrosis. The lamb had thrived at birth, but then became listless and died despite treatment. Histopathology showed that the lamb had also been suffering from an underlying chronic nutritional myopathy involving skeletal and cardiac muscle.

Reproductive tract conditions

In 2006, a total of 466 flock owners submitted material to their local SAC Centres following abortion outbreaks. Each year, a dozen or more different infectious agents are recorded as the cause of abortion outbreaks. This season the two most common diagnoses in Scottish flocks were Chlamydophila abortus infection and toxoplasmosis (figure 2; use PDF link on right), which together accounted for slightly more than half of diagnosed sheep abortion outbreaks in 2006. Although still a significant proportion of the total, this is less than the two thirds of the diagnosed outbreaks that were attributed to these infections in the 1990s. The most likely explanation for this relative decrease in importance is the availability of an effective live vaccine to control both conditions.

From the 2006 statistics we see that other common causes of abortion included the bacterial organisms Campylobacter, Listeria and Salmonella. The "Other" category is composed of a number of other pathogens that were encountered less frequently, including border disease virus and bacteria such as Arcanobacterium, Bacillus, Yersinia, Staphylococcus and Streptococcus species.

Nervous system disorders

Louping ill was diagnosed in a three-week-old Scottish Blackface lamb from a flock on the Isle of Skye. The group of lambs from which this individual came had been moved to an area known to carry ticks approximately one week previously. Six of the 42 lambs had shown signs of ataxia and tremors, and four had gone on to die after about four days. Blood collected from one of the fatalities had antibody to louping ill virus detected at a titre of 1/640 and composed entirely of IgM, confirming recent virus infection.

The owner of a flock in the Ayr region reported that gimmers in the flock had been giving birth to small, weak and non-viable lambs. When two lambs were submitted alive for examination there were marked developmental lesions in the brain and subsequent histopathology identified changes suggestive of border disease. However neither Border Disease virus antigen nor antibody could be detected in either lamb.

A three-year-old Shropshire ram at grass suffered a convulsion lasting some 3-4 minutes. On recovery the animal was able to sit normally, but remained ataxic and anorexic. Following housing the ram had a second convulsion and was euthanased. The only gross findings recorded at necropsy were of subcutaneous petechiation and pulmonary congestion. However, subsequent histopathology of the brain revealed severe lesions consistent with a diagnosis of listeriosis.